Dental offices may use a wide variety of mercury-containing products or chemicals. Most commonly used is dental amalgam which contains approximately 50% mercury, along with varying amounts of silver, tin and copper. Even dental offices that no longer use amalgam may still have mercury in pipes and drains from its use long ago.

When amalgam is allowed to escape down a drain, it comes in contact with water and the mercury then becomes a contaminant that must be removed by your local wastewater treatment plant. Once in the water, it can be difficult and costly to remove or reduce mercury to safe limits.

Where can mercury and amalgam be found in a dental office?

Amalgam waste can be found in different forms, including:

Non-contact amalgam (scrap amalgam) that is excess mix leftover at the end of a dental procedure);

Bulk mercury on hand if you were in practice before the pre-mixed capsules.

Mercury and amalgam may also be found in sewer pipes. Mercury can settle at a low point such as as a sump or trap and remain in the pipes of a facility for many years. Often, the slow dissolution of the mercury in a sump, trap or pipe is enough to cause exceedance of mercury limits in wastewater even after best management practices are implemented. Hot spots in a facility's piping may appear where laboratories or equipment maintenance areas were located. Whenever traps or sumps are moved or cleaned, the solid contents should be treated as a hazardous waste unless proven otherwise.

Why the concern?

Mercury is Toxic:

Although mercury performs many useful functions, it is toxic and can impair the way we see, hear and function.

In the environment, a percentage of mercury undergoes a biological/chemical process and is converted to methylmercury, which is a more toxic form of mercury.

Mercury poisoning can attack the central nervous system in humans. Women of child-bearing age and children, especially those under the age of six, are most susceptible to mercury poisoning.

Stricter Regulation:

Wastewater treatment plants are facing increased regulatory attention for levels of mercury in the wastewater they treat and ultimately discharge into Indiana waters. As a result, treatment plants throughout the state need the cooperation of business, industry and citizens to minimize the amount of mercury escaping down the drain.

What can dental offices do to help?

Use precapsulated alloys and stock a variety of capsule sizes;

Recycle used disposable amalgam capsules;

Salvage, store and recycle non-contact amalgam (scrap amalgam);

Salvage (contact) amalgam pieces from restorations after removal and recycle the amalgam waste;

Use chair-side traps to retain amalgam and recycle the content;

Recycle contents retained by the vacuum pump filter or other amalgam collection device, if they contain amalgam;